/**
 * Copyright 2012-2020 The Feign Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */
package feign.okhttp;

import java.io.IOException;
import java.io.InputStream;
import java.io.Reader;
import java.nio.charset.Charset;
import java.util.Collection;
import java.util.Map;
import java.util.concurrent.TimeUnit;

import feign.Client;
import feign.Request.HttpMethod;
import okhttp3.Headers;
import okhttp3.MediaType;
import okhttp3.Request;
import okhttp3.RequestBody;
import okhttp3.Response;
import okhttp3.ResponseBody;

/**
 * This module directs Feign's http requests to
 * <a href="http://square.github.io/okhttp/">OkHttp</a>, which enables SPDY and
 * better network control. Ex.
 *
 * <pre>
 * GitHub github = Feign.builder().client(new
 * OkHttpClient()).target(GitHub.class, "https://api.github.com");
 */
public final class OkHttpClient implements Client {

	private final okhttp3.OkHttpClient delegate;

	public OkHttpClient() {
		this(new okhttp3.OkHttpClient());
	}

	public OkHttpClient(okhttp3.OkHttpClient delegate) {
		this.delegate = delegate;
	}

	static Request toOkHttpRequest(feign.Request input) {
		Request.Builder requestBuilder = new Request.Builder();
		requestBuilder.url(input.url());

		MediaType mediaType = null;
		boolean hasAcceptHeader = false;
		for (String field : input.headers().keySet()) {
			if (field.equalsIgnoreCase("Accept")) {
				hasAcceptHeader = true;
			}

			for (String value : input.headers().get(field)) {
				requestBuilder.addHeader(field, value);
				if (field.equalsIgnoreCase("Content-Type")) {
					mediaType = MediaType.parse(value);
					if (input.charset() != null) {
						mediaType.charset(input.charset());
					}
				}
			}
		}
		// Some servers choke on the default accept string.
		if (!hasAcceptHeader) {
			requestBuilder.addHeader("Accept", "*/*");
		}

		byte[] inputBody = input.body();
		boolean isMethodWithBody = HttpMethod.POST == input.httpMethod() || HttpMethod.PUT == input.httpMethod() || HttpMethod.PATCH == input.httpMethod();
		if (isMethodWithBody) {
			requestBuilder.removeHeader("Content-Type");
			if (inputBody == null) {
				// write an empty BODY to conform with okhttp 2.4.0+
				// http://johnfeng.github.io/blog/2015/06/30/okhttp-updates-post-wouldnt-be-allowed-to-have-null-body/
				inputBody = new byte[0];
			}
		}

		RequestBody body = inputBody != null ? RequestBody.create(mediaType, inputBody) : null;
		requestBuilder.method(input.httpMethod().name(), body);
		return requestBuilder.build();
	}

	private static feign.Response toFeignResponse(Response response, feign.Request request) throws IOException {
		return feign.Response.builder().status(response.code()).reason(response.message()).request(request)
				.headers(toMap(response.headers())).body(toBody(response.body())).build();
	}

	private static Map<String, Collection<String>> toMap(Headers headers) {
		return (Map) headers.toMultimap();
	}

	private static feign.Response.Body toBody(final ResponseBody input) throws IOException {
		if (input == null || input.contentLength() == 0) {
			if (input != null) {
				input.close();
			}
			return null;
		}
		final Integer length = input.contentLength() >= 0 && input.contentLength() <= Integer.MAX_VALUE ? (int) input.contentLength() : null;

		return new feign.Response.Body() {

			@Override
			public void close() throws IOException {
				input.close();
			}

			@Override
			public Integer length() {
				return length;
			}

			@Override
			public boolean isRepeatable() {
				return false;
			}

			@Override
			public InputStream asInputStream() throws IOException {
				return input.byteStream();
			}

			@Override
			public Reader asReader(Charset charset) throws IOException {
				return input.charStream();
			}
		};
	}

	@Override
	public feign.Response execute(feign.Request input, feign.Request.Options options) throws IOException {
		okhttp3.OkHttpClient requestScoped;
		if (delegate.connectTimeoutMillis() != options.connectTimeoutMillis()
				|| delegate.readTimeoutMillis() != options.readTimeoutMillis()
				|| delegate.followRedirects() != options.isFollowRedirects()) {
			requestScoped = delegate.newBuilder().connectTimeout(options.connectTimeoutMillis(), TimeUnit.MILLISECONDS)
					.readTimeout(options.readTimeoutMillis(), TimeUnit.MILLISECONDS)
					.followRedirects(options.isFollowRedirects()).build();
		} else {
			requestScoped = delegate;
		}
		Request request = toOkHttpRequest(input);
		Response response = requestScoped.newCall(request).execute();
		return toFeignResponse(response, input).toBuilder().request(input).build();
	}
}
